Casting ingots



CASTING INGO-TS Filed Aug. z5. 1921 a #-6 cf! Plz-g: 5- V 2 'zzwezvolAlca/11u50@ Patented Sept. 29, 1925.

ulNlTED STATES y A 1,555,237 PATENT oFFicE.

I ADOLF V'ERNER CARLSSN, OF XOLSVA, SWEDEN.

CASTING INcfoTs.- A

Application led August 25, 1921. Seria1 No. 495,151.

(GRANTED lUNDER THE rnovisrons or THE ACT on MARCH s, 1921, 41 STAT.vL., 131s.) E

To all lwhom t may concern:

Be it known that I, ADOLF VERNER CARLS- soN, av subject of the King ofSweden, residing at 'Kolsva, Sweden, have inventedl certain new anduseful Improvements inor Relating to Casting Ingots (for which I haveled application in Sweden, Nom-14, 1918, Patent No. 49,093, of April 21,1921; England, November 13, 1919, Patent No. 135,207 Norway, November25, 1919; Denmark, Nov. 12, 1919; arid Germany, November 27, 1919), ofwhich the following is a specification.

When casting steel in a sandmould or an ingot mould, the composition andthe temperature of the steel being such as to pro duce steel withoutblisters, a more or less deep funnel-shaped depression called the pipewill be formed in the upper port-ion of the ingot. The longerthe upperportion of the ingot can be kept in afluid state, the better canblow-holes which may appear in the ingotbe filled with molten metal fromportions higher up andthe smaller will be the pipe. To retard`soliditication in the upper portion, a number of different methods areemployed such as Y l (a) Building up or ramming the upper portion ofingot mould with ireproof material.

b) Pouring slag on the yfused steel.

- c) Supplying heat to the upper surface Vof the steel by ignitedcharcoal, thermite, or by electric heating.

Moreover, it is well known that carbon in some form `or other is used incombination with moulding material, thus for instance c'ores are filledwith coke for venting said cores, compressed carbon is introduced in thewalls of moulds for carburization or hardening of the steel cast, coresare made Yof lireclay or sand mixed withy powderedv graphite, and hollowcores have been made of a mixture, one element of which is combustiblematerial for the purpose of obtaining combustion when the metal is cast.

By the present invention heat, is transferred to the upper part of theingot mould thus retarding the solidiication of the dead head at thispart and allowing molten metal to flowdown and preventformation of pipeunderneath dead heads.

The present invention consists principally in ramming the walls of thefeeding head .heat is evolved.

or the dead head with a material evolving heat under the iniuence ofthecastmetal and transferring heat to the dead head, said heat-evolvingmaterial being mixed with strengthening ingredients and, if desired,acting as a heat insulator and protected against n contact with themetal. Materials of this character are charcoal, coal and coke in theform of powdered or crushed to grains 'of suitable size and preferablymixed with clay and other ingredients required for obtaining thenecessary rigidity of the mould when rammingit and drying the material.The vwalls of the dead head or feeding head are preferably coated withblacking, or they are given a thin lining of some flreproof paste toprevent the molten metal from coming into contact with the v.charcoaland thereby absorbing carbon. Preferably the feeding head made in thiway is only partly filled with metal, when casting. Abovethis bodyofmetal there is then deposited a layer of a -material, such ascharcoal, whichwill evolve heat under the influence of the castmeta1,-an :insulating stratum being preferably arrangedV in known mannerbetween the molten metal and the charcoal, in order to preventabsorption of carbon. In accordance with this invention, the saidinsulating stratum may consist of molten slag or fused metal, thespecific gravity of which is lower than that of the metal thereunder.The lslag cover can,

however, be omitted if the charcoal is ap-.

plied only after the solidification of the upper surface ofl the metal,an insulating stratum preventing absorption of carbon having thus been-formed already through the said solidifying action of the metal.

Any heat-evolving material can be a'dvantageously used, provided thatthe heat from the fused metal causes combustion of same, or -gives riseto a reaction whereby To illustrate the method, Figures 1 and 2 of theaccompanying drawing show a/ runner opening or feeding head'in verticalsection, the said'gures being illustrative of the novel featuresaccording to the invention, whereas Figure 3 isa vertical section ofa-runner opening as heretofore known.

In Figure 1, a is the fused metal filling up the mold to .the level b-b.c is the sand mold, and d is 'the dead head in 'which is rammed theheat-evolvingpand heat-insulat-- solidified' stratum of the metal a1itself, thev same having the position h, shown by dotted lines. e

Figure 2shows the appearance of the metal after solidication. The topsurface has then sunk down evenly and assumes the position indicated by-the broken line b1 b, b1. The section shows a perfectly dense material,and the steel practically holds as much carbon in the upper part as inthe lower part of the ingot.

Figure 3 shows the same metal cast in an ordinary sand mold, the ingotbeing shown immediately after casting and solidiication of same. In thelfused state the metal fills the mold up to the level b2 U2, that is tosay as high up as in Figure 1.` This surface remains unchanged, that isto sayl the metal solidifies at the surface and remains at this level.The solidification also begins immediately from the walls of the feedinghead and, in fact, from the walls of the entire vmould, while thecentral portions of the metal arestill molten. The solidification iscontinued' from the surface inwardly,the metal shrinks, and the metallfrom the middle of the up er part sinks down, but when the metal at t etop surface and atthe walls of the feeding head has solidified, themetal cannot sink any further, this resulting in the formation of a`hollow-space or pipe, having an approximate vform and 'extensionasshownatkinFigure3- g v The present invention/is,particularlyapplicable to steel castings, The dead heads in steel castings serve thesame-purpose as the dead head (taken in the meanin of the metal cast inthe feeding head) o ingots made with feeding heads, or the upper portionof ingots made without a feeding,y head, that is to say they vareemployed as reser' `voirs for fused metal, introduced to fill hollowspaces appearing in the ingot during the solidification of'same. To thisend the size of the dead .headsmust be considerable, as only a smallportion of thev metal cast into the dead head is effective, filling thespace cavities in the ingot, the greater part of the metal solidifyingin the dead head around the walls. It is the cooling from the wallsthathas to be prevented, this being brought about by making the wall soas to evolve heat, when coming in contact Awith the metal. The fusedmetal coming in contact with the walls, the carbon is caused to glow andevolves heat, thereby counteracting the radiation of heat from the metaland thus retarding the solidification. The ineffective part of the deadheads, which is rammed in the known manner and which can be used only asscrap iron, ordinarily amounts to more than half the weight of thefinished steel casting, counted on the average of the whole production,the waste of Amaterial thus being considerable.

' Large dead heads have aV disadvantageous iniuence also on the qualityof the' casting, that is to say, in so far as they are acting to theformation of cracks due to shrinking as well as to Ablow holes in thematerial.

The cracks are formed when on the cooling of the metal and the shrinkingof it caused thereby, the strength of the material is insuiiicient toresist the stresses arising by the mold preventing the free shrinking ofthe metal. Blcw holes will arise in that part of the section, 'which isthe last to solidify, when on the solidifying of the metal the volume isreduced and the space cavity forming cannot be iilled with fused metalfrom other parts. High temperature and a slow solidification and coolingact to produce cracks and blow holes. The solidi fication isacceler-ated, when the heat of the metal is quickly led off by-the wallof the mould and thus a low temperature of the mould wall is anadvantage, conditions oth erwise remaining'thev same.

The steel havingbeen cast in the mould, it will be cooled by the coldwalls of the but the more metal passing throu h is to say thetemperature of the metal running from the ladle.

Steel castings being mostly 'cast by bottom gate, that is to say, byintroducing the steel into the bottom partA of the mold, the steelfilling the mould from the Vbottom upwards, the mater-ial, which fillsthe feeding heads, first passes through thev mould. Even if the pouring.is I ing also practised, when the metal reaches the feeding head, thatis ,to say when the metal has just filled the mould proper, and thesteel is then poured into the feedlng heads in order to obtain hottermetal in the latter, the pouring of the metal evidently 1s carried o'utfirst into one and then into another feeding head, but as the feedingheads communicate through the mould, the steel obviously passes throughthe latter. Thus, the larger the volume of the feeding "heads relativelyto the mould, the 'more metal will pass through the mould, the less willbe the cooling of the metal and the greater the heating. of the Walls ofthe mould, the slower does the solidificationtake lace and the greaterwill be the tendency o cracking mterrupted, such procedure beL heads inthe manner set forth with a material evolving heat bythe influence ofthe metal, the feeding heads are rendered more 'efficient and thus theirvolume can be reduced so as to counteract crackings and blow holes.

It is to be understood thatthe heat-evolving material, such as charcoal,added to the metal, must not come into contact with fused metal, thisbeing prevented according to the present method by applying eithermolten slag or fused metal of a lower specie gravity than the metalitself, in which case the melting temperature of the slag or the appliedmetal is utilized,or, in known manner, there may be added a materialsuch as borax, which affords. an insulating stratum and which is causedto glow or melt by the metal, in which case, however, part of the heatis taken from the metal. It is also possible to mix the heat-evolvingmaterial, such as carbon in some form or other, with suitable substancesgiving a slag of high fusibility, for instance lime and infusorlal earthor powdered glass, and to cover the surface with this mixture thusproducing a molten, ,an insulating stratum between the carbon and theiron. It is, moreover, possi-v ble to let the top surface of the metalsolidify and immediately thereafter lapply the charcoal. The point is toget the charcoal burning so as to evolve heat to the metal andsimultaneously toN prevent; .the charcoal from coming in direct contactwith the fused metal.

The present method is particularly applicable to steel, but mayobviously be used also in casting iron and other metals.

wWhat' I claim as new and `desire to secure by Letters Patent of theUnited States is 1. A method of preventing the formation of pipe iningots and castings and of reducing the dead heads thereof, and thus ofcounteracting cracks and blow holes in castings, consistlng in rammingthe walls of the feeding head or the dead head with a material, such ascoal breeze, evolving heat under the influence of the cast metal and`transferring heat to the dead head, said heat-evolving material beingmixed with strengthening ingredients and acting.Y as a heat insulator.

2. A method according to claim 1, in which the heat-evolving material.is mixed lyvitth clay or the like for the purpose speci- 3. In a methodaccording to claim 1 lacing an insulating stratum between the used.metal and the heat-evolving material in order to prevent absorption ofthelatter.

4. In a method according to claim 1, allowingthe top surface of themetal `to solidify and thus form an insulating stratum above which alayer of heating material, as charcoal or the like, is placed andignited in known manner. A

`5. A mould having the walls thereof rammed with a material, such ascharcoalbreeze which is. heat-insulating and heatevolving under' theinfluence of the metal for the purposes specified. l

In testimony whereof I affix my signature.

ADOLFYVERNER CARLSSON.

